BRATISLAVA, Slovakia — Defense ministers from NATO on Friday endorsed the ambitious counterinsurgency strategy for Afghanistan proposed by Gen. Stanley A. McChrystal, giving new impetus to his recommendation to pour more troops into the eight-year-old war.

General McChrystal, the senior American and allied commander in Afghanistan, made an unannounced appearance here on Friday to brief the defense ministers on his strategic review of a war in which the American-led campaign has lost momentum to a tenacious Taliban insurgency.

“What we did today was to discuss General McChrystal’s overall assessment, his overall approach, and I have noted a broad support from all ministers of this overall counterinsurgency approach,” said NATO’s secretary general, Anders Fogh Rasmussen.

The acceptance by NATO defense ministers of General McChrystal’s approach did not include a decision on new troops, and it was not clear that their judgment would translate into increased willingness by their governments, many of which have been seeking to reduce their military presence in Afghanistan, to contribute further forces to the war.

But it was another in a series of judgments that success there could not be achieved by a narrower effort that did not increase troop levels in Afghanistan substantially and focused more on capturing and killing terrorists linked to Al Qaeda — a counterterrorism strategy identified with Vice President Joseph R. Biden Jr.

The NATO briefing, though held privately, thrusts General McChrystal back into the debate over what President Obama should do about Afghanistan — a role that has raised tensions between the general and the White House in the past, and even drawn a rebuke from his boss, Defense Secretary Robert M. Gates.

NATO’s support got no official reaction from the White House. But an administration official noted that an endorsement by defense ministers was not the same as an endorsement by the alliance’s political leadership. Other officials were emphatic that Mr. Obama would not be stampeded in his deliberations and suggested that the NATO statement should not be taken as evidence that the White House had made a decision about how to proceed.

“In no way, shape or form are the president’s options constrained,” said Richard C. Holbrooke, the administration’s special representative for Afghanistan and Pakistan, speaking to reporters at the State Department.

General McChrystal’s review calls for adopting a full-scale counterinsurgency strategy that would protect population centers and accelerate training of Afghan Army and police units — both of which would require significant numbers of fresh troops. NATO diplomats noted that it was difficult to see how an acceptance of this broad strategy could be viewed as anything but an endorsement of the need to increase both military and civilian contributions.

Mr. Gates, who has kept his views about additional troops close to his vest and has discouraged his commanders from lobbying too publicly for their positions, declined to be drawn out on this assessment.

“For this meeting, I am here mainly in listening mode,” Mr. Gates said in Bratislava after the NATO briefing, although he noted that “many allies spoke positively about General McChrystal’s assessment.”

Mr. Gates said the administration’s decision on Afghanistan was still two or three weeks away, and he cautioned that it was “vastly premature” to draw conclusions now about whether the president would deploy more troops. He said that allied defense ministers had not voiced concerns about the administration’s decision-making process.

Although NATO will not meet until next month to decide whether to commit more resources to Afghanistan, Mr. Gates did reveal that he had received indications that some allies were prepared to increase their contributions of civilian experts or troops, or both.

Britain and other NATO members have had their own fractious political debates over troop levels. A retired top general in Britain recently said that the government of Prime Minister Gordon Brown had rebuffed his requests for more troops, a charge Mr. Brown denied.

Separate from his strategic review, General McChrystal has submitted a request for forces, which is now working its way through both the American and NATO chains of command.

The options submitted by General McChrystal range to a maximum of 85,000 more troops, although his leading option calls for increasing forces by about 40,000, according to officials familiar with the proposal.

The pressure for more troops was a theme throughout the day at the NATO meeting, as other senior international representatives told defense ministers of the need to increase their commitments in order to succeed in Afghanistan.

The United Nations special representative for Afghanistan, Kai Eide, who also flew to the Slovakian capital to meet the ministers, stressed that “additional international troops are required.” He also told the allies, “This cannot be a U.S.-only enterprise.”

Mr. Eide acknowledged that it might be difficult to rally public support for force contributions while allegations of election fraud continued to taint the government of President Hamid Karzai.

Senior NATO officials made clear that additional commitments should go beyond combat forces to include trainers for the Afghan Army and police force, as well as civilians to help rebuild the economy and restore confidence in the government.

“What we need is a much broader strategy, which stabilizes the whole of Afghan society, and this is the essence in the recommendations presented by General McChrystal,” said Mr. Rasmussen, the NATO secretary general. “This won’t happen just because of a good plan. It will also need resources — people and money.”

General McChrystal was not scheduled to make any public comments here. The general’s reticence was not unexpected, as some administration officials have criticized his recent statements as an attempt to press the White House to act.

The general and his aides have denied they were playing politics. General McChrystal said in a recent interview that success required a unified, government-wide strategy.

NATO officials assessing the potential for allied troop contributions said that delicate negotiations were under way, and that NATO capitals were watching the Obama administration for signals even while they sent signals of their own.

Thom Shanker reported from Bratislava, and Mark Landler from Washington.

A version of this article appears in print on October 24, 2009, on page A1 of the New York edition with the headline: NATO MINISTERS SUPPORT GENERAL ON AFGHAN WAR. Order Reprints|Today's Paper|Subscribe